Focal length equivalents?

[hugh_croft]

Hi. I've just bought a new lens for my E400 which 'goes to' 150mm.

I used to have a Canon 300D which 'went to' 200mm.

Which lens 'goes further' and what is a common reference measurement?

I did try 'Search' Thanks. Hugh

[Hector Javkin]

They "go" about the same. The common reference measurement is the field of view for 35mm film and for cameras like the Canon 5D. The E400 with a 150mm lens has the same field of view as the 35mm camera would have with a 300mm lens. The Canon with the 200mm has the same field of view as a 35mm camera with a 320mm lens. The difference is not important.

[hugh_croft]

Thanks, Hector.

[rroberto]

Enjoy your new camera Hugh, but be careful what questions you ask here, you don't want to

get a rant from Andrej.

[tim_huggins]

The "multiplication factor" of less than full frame sensors is just another marketing myth. The claim is that the 4/3 sensor doubles the focal length of a lens (i.e. a 50mm lens becomes a 100mm), and the factor for an APS sensor is 1.6 (i.e. a 50mm lens becomes an 80mm). They do nothing of the sort! The 50mm lens is still 50mm on any of these cameras. They simply crop the image so the subject takes up more of the area of a smaller frame.

[godfrey]

LOL ... Tim, that's about as clear as mud. ;-)

<br><br>

I use a nice field of view calculator which will give angular field of view in degrees for

horizontal, vertical and diagonal with whatever format and focal length you want to throw

at it. I hate all this nonsensical "crop factor" stuff. Why not just talk in terms of horizontal

field of view, or diagonal field of view. The calculator is available at <a

href="http://www.mat.uc.pt/~rps/photos/angles.html">http://www.mat.uc.pt/~rps/phot

os/angles.html</a>.

<br><br>

The usual "crop factor" is based on the relative length of the sensor diagonals, but 4/3

System format has a different format proportion compared to 35mm and Canon's 1.6x

crop sensors, so the equivalent focal lengths are always approximate. Here are some

precise numbers based on a Canon sensor size of 14.8 x 22.2 mm, an Olympus sensor

size at 13 x 17.3 mm, and 35mm film at 24 x 36 mm, with 200mm, 150mm and 300mm

lenses respectively:

<br><br>

<table border="1" cellpadding="4" align="center">

<tr>

<td>System</td>

<td>Focal Length</td>

<td>Horiz Degrees</td>

<td>Vert Degrees</td>

<td>Diagonal Degrees</td>

</tr>

<tr>

<td>Canon

"1.6x"</td><td>200.0</td><td>6.3533</td><td>4.2380</td><td>7.6323</td>

</tr>

<tr>

<td>Olympus

"2.0x"</td><td>150.0</td><td>6.6008</td><td>4.9625</td><td>8.2516</td>

</tr>

<tr>

<td>35mm

film</td><td>300.0</td><td>6.8673</td><td>4.5812</td><td>8.2490</td>

</tr>

</table>

<br><br>

As can be seen, the field of view values are quite close overall. Good enough for gummint'

work, eh?

<br><br>

Godfrey

<br>

[GerrySiegel]

Yes I can find the term "crop factor" less usable than your field of view chart, Godfrey. I am thinking that I once used 16mm cine film and when I switched down to 8mm there was a shorter focal length lens as standard for similar field of view. Meaning each system sensor gets its correct FL for covering a given field of view. I suspect this business will never get hashed out so it is clear to all. I could be wrong. gs